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Challenges of Grounding When Upgrading Substations and Security Fences

By Rob Schaerer

Abstract:

As power systems strengthen in order to keep up with changing system operations, the system will be capable of higher available fault currents. Electrical equipment on lines and in substations in turn must have increased fault duty and interrupt ratings. In substations specifically, the grounding systems need to adapt to the increasing fault current on the power system.

At the same time physical security requirements are increasing, resulting in many older substations requiring new fence upgrades. Many of these older sites did not have fence grounding that would meet today’s design practices, presenting challenges to properly ground the new security fence.

This paper presents the basics of grounding design and analysis to give the reader a brief background of the initial concerns. Some additional historical background on previous design approaches is included, which leads to some of the problems seen now as fault currents increase or as fences are upgraded. Based on an understanding of these concerns, several design approaches are presented both in new and existing substation grounding and security fence designs.

This paper was presented at the 2018 CIGRE US National Committee Grid of the Future Symposium.